TY - JOUR
T1 - Multitechnique Analysis of the Hydration in Three Different Copper Paddle-Wheel Metal-Organic Frameworks
AU - Terracina, Angela
AU - McHugh, Lauren N.
AU - Todaro, Michela
AU - Agnello, Simonpietro
AU - Wheatley, Paul S.
AU - Gelardi, Franco M.
AU - Morris, Russell E.
AU - Buscarino, Gianpiero
N1 - Funding Information:
The authors would like to thank people of the LABAM group ( http://www.unipa.it/lamp/ ) at the Department of Physics and Chemistry of University of Palermo and the REM group ( https://rem.wp.st-andrews.ac.uk/ ) at the School of Chemistry of University of St Andrews for useful discussions and support. The authors would also like to thank Dr. Daniel M. Dawson for the useful comments. The ATeN Center laboratory at the University of Palermo is acknowledged for the use of the Linkam cell and Raman spectrometer. Financial support by PJ-RIC-FFABR_2017 and the EPSRC grant EPSRC industrial CASE award (grant EP/N50936X/1) are acknowledged.
Publisher Copyright:
© 2019 American Chemical Society.
PY - 2019
Y1 - 2019
N2 - The structural instability in a humid environment of the majority of metal-organic frameworks (MOFs) is a challenging obstacle for their industrial-scale development. Recently, two water-resistant MOFs have been synthetized, STAM-1 and STAM-17-OEt. They both contain copper paddle wheels, like the well-known water-sensitive HKUST-1, but different organic linkers. The crystal lattice of both the MOFs undergoes a phase transition upon interaction with water molecules. Their unusual flexibility allows the controlled breaking of some interpaddle wheel Cu-O interactions in the so-called crumple zones, with a mechanism called hemilability, which is considered to have a crucial role for the stability toward water. In this work, we present a detailed investigation on the different effects of water exposure on the local and long-range structures of HKUST-1, STAM-1, and STAM-17-OEt. Electron paramagnetic resonance (EPR) spectroscopy has allowed us to characterize the different phases occurring during hydration of each MOF. In particular, we have identified and portrayed the moment of the adsorption of the first water molecule on each copper ion and shown that such soft hydration lead to a similar reversible evolution in all of the three MOFs. This aspect unveiled that the bulk water stability of the MOFs studied is unimportant at this early stage, whereas with a higher degree of hydration (more than few hours in our experimental conditions), we observe the three MOFs embarked on different paths, here carefully described. The evolution of HKUST-1 is not reversible because of its well-known tendency to hydrolysis, but, in contrast, we proved the reversibility of the water effects in STAM-1 and STAM-17-OEt even at the atomic scale level. Furthermore, for the first time, we report a Raman characterization of both STAM-1 and STAM-17-OEt, for each phase of the hydration. The data also include X-ray diffraction, nuclear magnetic resonance measurements, and Brunauer-Emmett-Teller surface area calculations of all the samples.
AB - The structural instability in a humid environment of the majority of metal-organic frameworks (MOFs) is a challenging obstacle for their industrial-scale development. Recently, two water-resistant MOFs have been synthetized, STAM-1 and STAM-17-OEt. They both contain copper paddle wheels, like the well-known water-sensitive HKUST-1, but different organic linkers. The crystal lattice of both the MOFs undergoes a phase transition upon interaction with water molecules. Their unusual flexibility allows the controlled breaking of some interpaddle wheel Cu-O interactions in the so-called crumple zones, with a mechanism called hemilability, which is considered to have a crucial role for the stability toward water. In this work, we present a detailed investigation on the different effects of water exposure on the local and long-range structures of HKUST-1, STAM-1, and STAM-17-OEt. Electron paramagnetic resonance (EPR) spectroscopy has allowed us to characterize the different phases occurring during hydration of each MOF. In particular, we have identified and portrayed the moment of the adsorption of the first water molecule on each copper ion and shown that such soft hydration lead to a similar reversible evolution in all of the three MOFs. This aspect unveiled that the bulk water stability of the MOFs studied is unimportant at this early stage, whereas with a higher degree of hydration (more than few hours in our experimental conditions), we observe the three MOFs embarked on different paths, here carefully described. The evolution of HKUST-1 is not reversible because of its well-known tendency to hydrolysis, but, in contrast, we proved the reversibility of the water effects in STAM-1 and STAM-17-OEt even at the atomic scale level. Furthermore, for the first time, we report a Raman characterization of both STAM-1 and STAM-17-OEt, for each phase of the hydration. The data also include X-ray diffraction, nuclear magnetic resonance measurements, and Brunauer-Emmett-Teller surface area calculations of all the samples.
UR - http://www.scopus.com/inward/record.url?scp=85074690951&partnerID=8YFLogxK
U2 - 10.1021/acs.jpcc.9b08159
DO - 10.1021/acs.jpcc.9b08159
M3 - Article
AN - SCOPUS:85074690951
SN - 1932-7447
JO - Journal of Physical Chemistry C
JF - Journal of Physical Chemistry C
ER -